Pulsed Power Research Articles

Synergistic Enhancement of Energy Storage Performance in NaNbO3-Based Lead-Free Relaxor Ferroelectrics via Weakly Coupled Relaxation Behavior.

Advancements in pulsed electronic power systems depend significantly on high-performance dielectric energy storage ceramics. Lead-free NaNbO3-based energy-storage ceramics are important materials for next-generation pulsed power capacitors owing to their large polarization and bandgaps. However, the high energy loss caused by the antiferroelectric-ferroelectric phase transition leads to low recoverable energy storage density and efficiency, which hinders its practical application. Herein, a weakly coupled relaxor ferroelectric is designed via chemical modification, which realises a high recoverable density of 12.7Jcm- 3 and a decent η of 85.7%. Compositionally induced domain-size refinement effectively delays low-field polarization saturation and elevates η. Experimental characterization and theoretical-model analysis confirm that the superior comprehensive energy-storage performance is attributed to the component-driven formation of polar nano-micro-regions with weak interactions, which suppresses the polarization hysteresis and improves the polarization difference. This study demonstrates that component-driven construction of weakly coupled relaxor ferroelectric materials is an effective strategy for achieving ultrahigh energy-storage characteristics.

Superior Capacitive Energy Storage at High Temperature of All-Organic Aromatic Polymer via Enhancing Conjugate Angle between Benzene Rings.

High-temperature polymer capacitors with superior energy storage density are considerable and desirable components in advanced power pulse, electrical, and energy conversion systems. However, due to the π-π conjugated benzene ring structure, carriers migrate through polyimide (PI) chains, reducing discharge energy density (Ue) and charge-discharge efficiency (η) at high temperature. Here, the ether (-O-) and isopropylidene (-C(CH3)2-) groups are purposefully introduced into the position between the benzene rings to increase the conjugate angle in PI chains, and spatial folded chains are designed to impede charge transport at high temperature. The experimental results show both surface charge dissipation rate and leakage current decrease at 150 °C when (-C(CH3)2-) groups increase, indicating that deep traps that hinder charge transport are introduced in the chains. Hence, the breakdown strength of the designed polymer (BAPP+BPADA) significantly increases, and its Ue and η reach 3.87 J/cm3 and 90% at 150 °C, 2.74-times the energy density of the pristine PI film. Simultaneously, the BAPP+BPADA film exhibits excellent discharge response and cycling charge-discharge stability, which have the potential to be applied in functional devices under extreme conditions. The work performs a superior energy storage all-organic film and offers a strategy that regulates the chains' spatial topological structure for future aromatic polymers for high-temperature energy storage.

Methodology for determining the technical condition of the pulse power supply unit in dynamic mode

Since the power supply unit is an integral part of any electronic device, to ensure high quality and reliability of its operation, it is necessary to periodically check its operational characteristics and the structural solutions used in it. The lack or untimely verification procedures jeopardizes the functioning of the entire device and leaves the user vulnerable to the likely onset of sudden failures and subsequent potentially unpleasant situations. It should be borne in mind that the element base (workmanship) of the power supply units does not differ from the quality of the element base of the entire device, while this unit is an intermediary between the power supply network (parameters of the characteristics and state of the power supply network) and the main device (technical condition and adequacy of the user when using it). Therefore, the durability of the main equipment depends on the efficiency and correctness of the functioning of the power supply, the stability of its parameters. In case of a critical state of the equipment, the power supply unit itself contains a fuse (automatic emergency shutdown system), while the operation of the fuse does not allow to determine the cause (source) of the critical state (network - power supply unit - main equipment - violation of operating rules). Replacing the fuse, or replacing the power supply does not guarantee the final solution to the problem of technical diagnostics. Given the ever-increasing complexity and high cost of modern electronic devices (including those with elements of artificial intelligence), the issue of timely diagnosis of potential power supply malfunctions is critically important. Therefore, the development of scientifically sound approaches to determining the technical condition of power supplies and localizing its faults is an urgent task

The Effect оf Repeated Exposure to Complexly Organized Electromagnetic Radiation on the Rats Behavior in the “Open Field” Test

In experiments on Wistar rats, males and females, the effect of 3-fold (1 hour a day with an interval of three days) and multiple (8 weeks, 5 days a week, 2 hours a day) pulsed-modulated electromagnetic radiation on the tentative research reactions was studied, tested by the “open field” method. The animals were irradiated in an anechoic chamber in the zone of the formed wave of the microwave source (a block of 10 generators carrying frequencies from 1 to 4 GHz, the total pulse power density 300 microW/cm2, pulse duration 25 ms, sweep cycles 1–6 Hz, cycle turn-around time 30s). It has been showed that exposure to such parameters can cause a stress reaction and an impairment of long-term memory in some irradiated animals, and female rats were more sensitive to the action of microwaves, than males. This reaction was transient and 1.5–2 months after cessation of irradiation, the behavior of the animals was restored. However, there is a danger that with constant exposure to microwaves, which, for example, occurs in mobile users, such behavior deviations may become fixed and clinically significant.

Optimal Charging Current Protocol with Multi-Stage Constant Current Using Dandelion Optimizer for Time-Domain Modeled Lithium-Ion Batteries

This study utilized a multi-stage constant current (MSCC) charge protocol to identify the optimal current pattern (OCP) for effectively charging lithium-ion batteries (LiBs) using a Dandelion optimizer (DO). A Thevenin equivalent circuit model (ECM) was implemented to simulate an actual LiB with the ECM parameters estimated from the offline time response data obtained through a hybrid pulse power characterization (HPPC) test. For the first time, DO was applied to metaheuristic optimization algorithms (MOAs) to determine the OCP within the MSCC protocol. A composite objective function that incorporates both charging time and charging temperature was constructed to facilitate the use of DO in obtaining the OCP. To verify the performance of the proposed method, various algorithms, including the constant current-constant voltage (CC-CV) technique, formula method (FM), particle swarm optimization (PSO), war strategy optimization (WSO), jellyfish search algorithm (JSA), grey wolf optimization (GWO), beluga whale optimization (BWO), levy flight distribution algorithm (LFDA), and African gorilla troops optimizer (AGTO), were introduced. Based on the OCP extracted from the simulations using these MOAs for the specified ECM model, a charging experiment was conducted on the Panasonic NCR18650PF LiB to evaluate the charging performance in terms of charging time, temperature, and efficiency. The results demonstrate that the proposed DO technique offers superior charging performance compared to other charging methods.

Effect of Pulsed Current Treatment on Microstructure and Properties of 304 Stainless Steel Ultra-Thin Strip after Rolling

The annealing process is usually used to heat-treat cold-deformed 304 stainless steel to improve its microstructure and properties to a certain extent; however, it requires a high temperature and a long time. Because the thickness of the ultrathin strip reaches the micrometer level, it has only one or several layers of grains in the thickness direction, and the control of morphology and performance is complex. In this study, pulsed current loading was used to replace traditional annealing for treating ultrathin strips of cold-rolled 304 stainless steel. After loading a 25 W pulsed current treatment for 5 min on the cold-rolled sample, which had a thickness of 0.035 mm and width of 6 mm, complete recrystallization occurred, and the mechanical properties were significantly improved. At this point, the measured temperature was 540 °C. When annealing was used to treat the sample with the same temperature and for the same duration, the microstructure was still dominated by deformed crystals, and the mechanical properties were poor. When annealing was used to obtain a microstructure and properties similar to those obtained via 25 W electrical treatment, the required annealing temperature and time were 810 °C and 60 min, respectively. Pulsed current can increase the vacancy diffusion flux in the sample, accelerate the atomic movement, reduce the recrystallization activation energy, and make the cold-rolled 304 stainless steel ultrathin strip completely recrystallize at a lower temperature and in a shorter time. As the current power continued to increase, the recrystallized grains grew. When the pulsed current power was increased to 25 W, the recrystallized grains grew negligibly. Both recrystallization and grain growth have power thresholds. This study provides a novel approach for regulating the microstructure and mechanical properties of ultrathin cold-rolled 304 stainless steel strips.

Investigation of a fast gate driver based on a half-turn planar transformer.

This paper presents a magnetically isolated gate driver for the fast switching of IGBT (Insulated Gate Bipolar Transistor) in compact pulsed power sources with sharp rising edges and flat-top pulses for the application of electromagnetic launch and food processing. The proposed gate driver is implemented based on a planar transformer with a half-turn winding arrangement to increase the amplitude of the driving voltage pulse. With the half-turn winding arrangement, the leakage inductance of transformers decreases by 31.1% compared to the interleaving structure. This decrease enables a fast rise time of the driving voltage pulse. Furthermore, the gate drivers are used to drive the IGBT switching a Blumlein pulse forming network. The results show that the di/dt of the applied commercially available Si IGBT is about 10.10 A/ns with a gate voltage of 50V and a gate capacitance charging time of about 88ns, proving the effectiveness of the gate driver and providing a high-performance driving scheme for the fast switching of Si IGBT.

Design of a Novel 16‐Way Short Pulse Power Divider Based on Transmission Line Transformer

ABSTRACTThis article presents a 16‐way short pulse power divider (PD) with the same input and output impedance based on the transmission line transformer (TLT) principle. Different from the traditional multi‐channel PD composed of impedance tapered transmission lines and PDs in parallel structure, the novel 16‐way PD is cascaded by multi‐stages of series‐parallel structure, which avoids the process of impedance transformer and improves the compactness of the device, as well as the transmission efficiency. It was composed of four stages of the novel series‐parallel constructure converted from coaxial waveguide to microstrip line. And to control the energy dissipation, a unified ground of the output ports was built, and the short‐ended metal shell was loaded between every stage. This 16‐way PD was fabricated and measured. The measured return loss of the PD is less than −16 dB from 440 MHz to 6 GHz, and less than −10 dB from 270 MHz to 6 GHz. The measured peak gain is more than 0.83 when input by a Gaussian pulse with tFWHM = 250 ps (FWHM: full‐width half maximum).

Advancing energy storage capabilities in 0.7BNST(1-x)-0.3BLMNx lead-free dielectric ceramic materials

Lead-free ferroelectric ceramics with a composition of 0.7(Bi0.5Na0.5)0.7Sr0.3Ti(1-x)O3-0.3Ba0.94La0.04(Mg1/3Nb2/3)xO3 (abbreviated as 0.7BNST(1-x)-0.3BL(MN)x, 0 ≤ x ≤ 0.12) were prepared using solid-phase sintering method, involving co-substituting at A and B sites. High recoverable energy density (Wrec) of 3.54 J/cm3 and energy efficiency (η) 85.49% are achieved at an electric field of 270 kV/cm. Furthermore, these ceramics exhibited excellent temperature and cycle stability at 120 kV/cm (within 25 °C–150 °C, Wrec fluctuation range <14 %; under 1∼106 cycles, the Wrec fluctuation range <5 %). In terms of dielectric performance, they exhibited a high dielectric constant (εr∼4540), an extremely low dielectric loss tanδ of <0.04 (30 °C–300 °C), and good temperature stability with Δε/ε150 °C ≤ ±15 % (−19.5 °C–233.4 °C). During the charging and discharging process, these ceramics demonstrated a high energy density (Wd) of 1.2 J/cm3, a power density (PD) of 61.7 MW/cm3, and an extremely short discharge time (t0.9) of approximately ∼0.11 μs＀ This study has improved the dielectric energy storage performance of BNT-based lead-free piezoelectric ceramics, making them suitable for use in pulse power devices.

Low Pass Filter Based Lithium‐ion Battery Equivalent Circuit Model With High Accuracy

AbstractThe equivalent circuit model (ECM) of lithium batteries provides a simplified way to describe their output behaviors. In this paper, a low pass filter‐based ECM of lithium battery is proposed with high accuracy. A voltage source is employed to represent the capability of the lithium battery to store energy chemically, a RC branch paralleled with the voltage source represents the charge transfer process. This RC branch acts as a low pass filter, and the capacitance buffers the charges during charging or discharging process, and this explains the dynamic voltage recovery process. However, with the traditional RC branches‐based ECM, the dynamic voltage is realized by the resistance in parallel with the capacitor, which discharges the capacitor and the RC branch is series‐connected with the voltage source. The proposed ECM is compared with the 1‐RC Thevenin model, which has the same number of model parameters with the proposed model. The parameters are obtained by the hybrid pulse power characterization (HPPC) test. The output voltage accuracy of the 1‐RC Thevenin model and the proposed model with LFP battery and NCM battery is verified with different test conditions. The experimental results show that the proposed ECM has higher accuracy, this validates the correctness of the proposed model.

Tape‐Casting Lead‐Free Dielectrics Permit Superior Capacitive Energy Storage Performance

AbstractDielectric capacitors have garnered significant attention for their promising attributes in advanced pulse power systems of the future, owing to their rapid charge/discharge capabilities, high power density, and remarkable stability. Whereas environmentally friendly lead‐free ceramics are facing serious challenges of low breakdown strength, poor energy storage density, and/or conversion efficiency, which has been an obstacle to developing desirable dielectric capacitors. In this study, high‐quality ultrathin (&lt;20 µm) lead‐free ceramic dielectrics are successfully produced via the tape‐casting method. The local structural characteristics of these ceramics are verified using piezoresponse force microscopy and aberration‐corrected scanning transmission electron microscopy. By introducing Ta5+ ions into Bi0.39Na0.36Sr0.25TiO3 ceramics, the polar clusters tend to decrease together while the maximum applied electric field tends to increase. This phenomenon can be attributed to the decreased grain size and complex polar structure characterized by extremely small polar clusters, enabling the simultaneous achievement of high applied electric field, large polarization, and minimized polarization hysteresis. Notably, the tape‐casted lead‐free ceramics exhibited exceptional comprehensive energy storage performance with a recoverable energy storage density of ≈10.06 J cm−3 and an efficiency of ≈93% under a high electric field of 915 kV cm−1, surpassing the capabilities of most reported lead‐free ceramics. This work offers a viable solution for developing lead‐free ceramic dielectrics with outstanding energy storage capabilities.

High-power, frequency-doubled all-polarization-maintaining fiber laser system at 925 nm.

We demonstrate a high-power 925-nm pulsed laser system based on a frequency-doubled, all-polarization-maintaining (PM) fiber laser source operating at 1.8 µm. The seed is a figure-9 mode-locked oscillator, which incorporates a nonlinear amplifying loop mirror. After power scaling and pulse compression, the 1.8-µm laser source can provide femtosecond pulses with a repetition rate of 31.3 MHz and an output power of 2.24 W. Through frequency doubling in a nonlinear crystal, the 925-nm laser delivers a pulse duration of 503 fs and an output power of 818 mW, which is the highest power provided by all-PM fiber laser systems at this wavelength, as far as we know. Furthermore, this 925-nm all-PM fiber laser is employed as the excitation light source for two-photon microscopy (TPM) and second-harmonic generation (SHG) microscopy.

Double enhancement of energy storage density in relaxor ferroelectric 0.8BaTiO3-0.2BiScO3 by Li defect-regulated strategy

To meet the ever-increasing demands for pulsed power technologies, the development of lead-free dielectric ceramics with a large energy storage density (Wrec) and high energy storage efficiency (η) is crucial for enhancing the electrical performance of power capacitive devices. The conventional solid-solution, while effective in suppressing long-range order and improving energy storage performances, often results in a reduction of maximum polarization. This reduction necessitates the application of a larger electric field to obtain a relatively high Wrec. Herein, an effective strategy to enhance Wrec again via inducing Li-related defect dipoles is proposed. By introducing (Bi0.5Li0.5)TiO3 into 0.8BaTiO3-0.2BiScO3 matrix, the polarization contribution from defect dipoles together with intrinsic polarization induces an at least two-time enhancement in Pmax. Our findings indicate ∼62.9 % enhancement in the Wrec of 0.8BT-0.2BS, elevating from 2.56 J cm−3 to 4.17 J cm−3 at electrical field of 300 kV cm−1, while preserving an energy storage efficiency of 90.35 %. Furthermore, it also exhibits good thermal stability with the variations of ΔWrec < 3 % and η< 5 %. This research introduces a novel strategy for defect regulation strategy in the design of high-performance dielectric materials, which is expected to expedite the optimization of the advanced energy storage capacitors.

Enhanced energy storage performance of lead-free Sr0.7Bi0.2TiO3 ceramics via tape casting

Abstract The development of pulsed power technology demands high energy storage density dielectric materials. In this study, Sr0.7Bi0.2TiO3 relaxor ferroelectric (rFE) ceramic thick films were prepared using a tape-casting process. The ceramics exhibit a dense structure and typical rFE hysteresis curves, achieving an energy storage density of 4.77 J cm−3 and efficiency of 94.4%, attributed to the high polarization intensity, low remnant polarization, and low hysteresis loss of rFE. Additionally, the material demonstrates good temperature stability. Moreover, the Sr0.7Bi0.2TiO3 ceramic thick films show advantages in charge-discharge performance, capable of discharging within hundreds of nanoseconds and achieving a power density of 137 MW cm−3. Overall, the Sr0.7Bi0.2TiO3 ceramic thick film exhibits a comprehensive performance advantage in terms of energy storage density, efficiency, and power density. Additionally, the material was fabricated using the tape-casting process, which is compatible with subsequent multilayer ceramic capacitor production, indicating potential for further performance enhancement.

Classical-quantum simulation of non-equilibrium Marshak waves

In the radiation hydrodynamic simulations used to design inertial confinement fusion (ICF) and pulsed power experiments, nonlinear radiation diffusion tends to dominate CPU time. This raises the interesting question of whether a quantum algorithm can be found for nonlinear radiation diffusion which provides a quantum speedup. Recently, such a quantum algorithm was introduced based on a quantum algorithm for solving systems of nonlinear partial differential equations (PDEs) which provides a quadratic quantum speedup. Here, we apply this quantum PDE (QPDE) algorithm to the problem of a non-equilibrium Marshak wave propagating through a cold, semi-infinite, optically thick target, where the radiation and matter fields are not assumed to be in local thermodynamic equilibrium. The dynamics is governed by a coupled pair of nonlinear PDEs which are solved using the QPDE algorithm, as well as two standard PDE solvers: (i) Python's py-pde solver; and (ii) the KULL ICF simulation code developed at Lawrence-Livermore National Laboratory. We compare the simulation results obtained using the QPDE algorithm and the standard PDE solvers and find excellent agreement.

Generation of switchable rectangular pulsed cylindrical vector beams in a 1.7 µm mode-locking all-fiber laser

In this paper, we demonstrate the generation of switchable rectangular pulsed cylindrical vector beams in a 1.7 µm mode-locking all-fiber laser by nonlinear amplifying loop mirror for the first time. Based on the nonlinear amplifying loop mirror mode-locking technology and mode selection coupler, the rectangular pulsed CVBs can be achieved and switched repeatedly and easily between the dissipative soliton resonance and noise-like pulse states. Furthermore, with the increasing of pump power, the duration of dissipative soliton resonance and noise-like pulse increase from 1.76 ns to 6.36 ns and 1.15 ns to 3.95 ns, respectively. In the meanwhile, both the peak power of dissipative soliton resonance and noise-like pulse are all clamped at 6 W all the time, showing the independence of clamped peak power and pulse type. Our work not only broadens wavelength range of switchable rectangular pulse, but also provides a novel pulse profile application of cylindrical vector beams.

Competing mechanisms of charge-induced electric field distortion and charge-involved neutralization on surface discharge

Charge-induced surface discharge poses a critical risk to the operational reliability of high-voltage direct current gas-insulated equipment and pulsed power system. In this study, we investigate the effects of charge-induced electric field distortion and charge involvement during surface discharge by separately depositing charge spots on two dielectric layers. The results show that deposited positive charges inhibit positive streamer development, whereas negative charges facilitate it, primarily due to electric field distortion induced by deposited charges. Nevertheless, the involvement of deposited charges in streamer development predominantly exhibits a neutralizing effect, exerting an opposite influence on the streamers. This highlights a competitive relationship between deposited charge involvement and electric field distortion. Additionally, the neutralization of deposited charges with electron avalanches reduces the impact of charge-induced electric field distortion, thereby mitigating its effects on discharge.

Low-frequency harmonic current suppression for a dc pulsed power supply based on improved ADRC

Low-frequency harmonic current suppression for a dc pulsed power supply based on improved ADRC

GEANT4 simulation for controlling and focusing of laser-accelerated proton beam for particle therapy using pulsed power solenoids

Laser-accelerated proton beams (LAP) have inspired innovative applications that can leverage proton bunch properties distinct from those of conventionally accelerated proton beams. A new multifunctional LAP beamline has been proposed, utilizing the GEANT4 toolkit, and the solenoids have been simulated using high-precision components.We present the design of the initial segment of the transport beamline and energy selection system for the effective transport of a radiation pressure acceleration source with a high energy spread. This study examines the effects of solenoids on proton beam quality, specifically focusing on profiles, FWHM, and transmission efficiency. The results obtained using our developed GEANT4 toolkit validate the analytical formulas and findings from the DYNAMION code regarding emittance and proton profiles. Additionally, the presented GEANT4 LAP beamline is capable of calculating the flux of secondary particles, such as neutrons and photons. It was observed that careful attention to the precise structure of the solenoids is critical.

A theoretical study of the output coupler reflectivity effect on the characteristics of Er+3 laser pulse at passively q-switching

The objective of this study deal the effect of the output coupler mirror reflectivity of laser system on behavior and characteristics (duration and energy) of erbium passive Q-switching laser pulse was studied theoretically. In the methods of the study, virtual passive Q-switching laser system consist of major elements such as erbium doped silica as an active medium, Cr+4: YAG crystal used as a saturable absorber, and the mirrors of resonator. Mathematical rate equations model has been used to describe the physical relationship between this element has been solved numerically by Rung - Kutta –Fehlberg method. The results showed regarding the pulse behavior, the increasing value of output coupler mirror reflectivity lead to decreasing of rising and falling time of pulse, so the emission of pulse occur in an advanced time. While regarding the pulse characteristics, the pulse was distinguishable by short duration and high energy, resulting high power of pulse when the output coupler mirror reflectivity increasing. Regarding of results discussion, the study attributes the results to a decrease of the initial and final population inversion density of active medium that results from the increasing value of output coupler mirror reflectivity. Therefore, it is possible to conclude in order to improve the characteristics of erbium passive Q-switching laser pulse; it is appropriate increase the value of output coupler mirror reflectivity within acceptable limits.